We don't have authoritative data on Soviet nuclear targeting during the Cold War. However, US planners for Civil Defense purposes assumed that essentially every airport was a potential target (because they could be used for supporting bomber operations) and that large industrial facilities were also possibly targets. The 1990 edition of FEMA's Risks and Hazards: A State by State Guide, which is evolved from these kinds of assessments, has at least three potential ground zeros in the immediate Charleston area, as you can see here. Whether these reflect actual Soviet targeting strategies and priorities is not known. (The locations of those ground zeroes are not arbitrary, but it can take some work to figure out what they are meant to be. Airports, industrial facilities, military facilities, and power plants are all common "targets" in this model.)